Brake drum having irregularly spaced chill fins extending from a squealer band

Abstract

A cylindrical brake drum including a flanged end and an open end having a squealer band in the shape of an annular ring and a multiplicity of chill fins irregularly spaced one to another and/or relative to a plurality of equally spaced airflow channels where the chill fins are cast into the squealer band and the outside surface of the brake drum where the chill fins are generally of a constant height with respect to the outside surface and then moving axially outward decrease in height to meet the outside surface and cause any casting porosities to move to a central region of the squealer band thereby reducing drum cracking due to localized hot spots thereby greatly improving the brake drum fatigue strength while minimizing the increase in overall weight and facilitating ease of manufacture.

I claim: 
     
       1. A brake drum comprising: a cylindrical braking drum having a flanged end opposite an open end and having an outer surface therebetween, said braking drum having an axis of rotation;   a squealer band in the shape of an annular ring formed on said outer surface in substantial close proximity to said open end, said squealer band having an outboard side facing opposite said open end;   a plurality of generally axially extending circumferentially equally spaced airflow channels formed in the outer surface of said cylindrical braking drum, said airflow channels being approximately rectangular in shape and extending from said squealer band to said flanged end, said channels having a depth of approximately 40 percent of a nominal thickness of said cylindrical braking drum, said channels having a minimum width of 6 percent of the diameter of said cylindrical braking drum; and   a multiplicity of generally axially extending chill fins, said chill fins being perpendicular to said outer surface and attached to said cylindrical braking drum and radially extending at a generally constant height from said outboard side of said squealer band to said outer surface, said chill fins irregularly circumferentially spaced relative to said airflow channels where at least one of said chill fins is attached to said braking drum within one of said airflow channels to promote chaotic airflow over said outer surface of said cylindrical braking drum.   
     
     
       2. The brake drum as set forth in claim 1, wherein said chill fins have a maximum height from said outer surface equivalent to the maximum height of said outboard side of said squealer band. 
     
     
       3. The brake drum as set forth in claim 1, wherein said chill fins are circumferentially positioned such that a separation angle between adjacent chill fins created from said axis of rotation extending radially through said chill fins has a maximum value of fifteen (15) degrees. 
     
     
       4. The brake drum as set forth in claim 1, wherein said chill fins have an axial length of 5 to 20 times the width of said chill fins. 
     
     
       5. A brake drum comprising: a cylindrical braking drum having a flanged end opposite an open end and having an outer surface therebetween, said braking drum having an axis of rotation;   a squealer band in the shape of an annular ring formed on said outer surface in close proximity to said open end, said squealer band having an outboard side facing opposite said open end;   a plurality of generally axially extending airflow channels formed into said outer surface of said braking drum, said airflow channels being generally rectangular in cross section and extending from said outboard side of said squealer band to said flanged end;   a plurality of generally axially extending chill fins radially extending from said outer surface of said braking drum to said outboard side of said squealer band, said chill fins having a height approximately equivalent to the height of said outboard side, said chill fins being structurally separate and distinct from said airflow channels;   where at least one of said chill fins contacts said outer surface of said braking drum within one of said airflow channels for promoting chaotic airflow over said outer surface of said cylindrical braking drum.   
     
     
       6. The brake drum of claim 5, wherein said chill fins are irregularly circumferentially spaced relative to said airflow channels. 
     
     
       7. The brake drum of claim 5, wherein said airflow channels have a depth of approximately 40 percent of a nominal thickness of said braking drum and a minimum width of approximately 6 percent of the diameter of said braking drum. 
     
     
       8. A brake drum comprising: a cylindrical braking drum having a flanged end opposite an open end and having an outer surface therebetween, said braking drum having an axis of rotation;   a squealer band in the shape of an annular ring formed on said outer surface in substantial close proximity to said open end, said squealer band having an outboard side facing opposite said open end;   a plurality of generally axially extending airflow channels formed in the outer surface of said cylindrical braking drum, said airflow channels being approximately rectangular in shape and extending from said squealer band to said flanged end, said channels having a depth of approximately 40 percent of a nominal thickness of said cylindrical braking drum, said channels having a minimum width of 6 percent of the diameter of said cylindrical braking drum, and   a multiplicity of generally axially extending chill fins circumferentially unequally spaced one from the other, said chill fins being perpendicular to said outer surface and attached to said cylindrical braking drum and radially extending at a generally constant height from said outboard side of said squealer band to said outer surface, said chill fins irregularly circumferentially spaced relative to said airflow channels where at least one of said chill fins is attached to said braking drum within one of said airflow channels to promote chaotic airflow over said outer surface of said cylindrical braking drum.